Design and optimization of an electromagnetic servo braking system combining finite element analysis and weight-based multi-objective genetic algorithms

The purpose of this paper is to show the design and optimization of a novel electromagnetic servo brake incorporating an Antilock brake system (ABS) function by Multi-objective genetic algorithms. To consider different design requirements, three types of Axisymmetric Finite element (FE) models were initially formulated parametrically to determine the braking force and position of the pusher at each instant during operation of the proposed device. Using a combination of the FE models and Weight-based multi-objective genetic algorithms (WBMOGA), the optimal geometry and dimensions of the proposed FE models were determined while maximizing the braking force of the device and minimizing both the current supplied by the battery and the weight of the assembly. Once an optimal configuration for each type of servo brake designed had been achieved, three prototypes were built and validated experimentally on a conventional test bench. Finally, the prototype that performed best of the three prototypes was mounted and tested on a hybrid test bench with a realistic ABS device. The good agreement between the results obtained from the simulations and those measured experimentally, suggests that the combination of FE models and WBMOGA may be used successfully to design and optimize any complex electromechanical device.     

Suspension modeling and optimization using finite element analysis

A finite element based optimization software Altair OptiStruct is used to optimize the design of suspensions in hard disk drives. Topology optimization, topography optimization and combinations of both techniques are used to optimize a contact start-stop suspension with respect to torsion, bending and sway mode frequencies. The suspension, gimbal, slider and airbearing are modeled. The airbearing is modeled with linear springs to represent stiffness in the z-direction, pitch and roll. Modal analysis is compared to experimental resonance data to verify the model. The results show that improvements of more than 50% can be achieved with respect to increasing sway or torsional modes.     

Multi-objective optimization of oblique turning operations using finite element model and genetic algorithm

Multi-objective optimization of oblique turning operations while machining AISI H13 tool steel has been carried out using developed finite element (FE) model and multi-objective genetic algorithm (MOGA-II). The turning operation is optimized in terms of cutting force and temperature with constraints on required material removal rate and cutting power. The developed FE model is capable to simulate cutting forces, temperature and stress distributions, and chip morphology. The tool is modeled as a rigid body, whereas the workpiece is considered as elastic–thermoplastic with strain rate sensitivity and thermal softening effect. The effects of cutting speed, feed rate, rake angle, and inclination angle are modeled and compared with experimental findings. FE model is run with different parameters with central composite design used to develop a response surface model (RSM). The developed RSM is used as a solver for the MOGA-II. The optimal processing parameters are validated using FE model and experiments.     

基于ANSOFT有限元分析的静电涂油机刀梁电极结构优化设计

按照静电涂油机涂油室的结构特点和实际工作条件,利用ANSOFT软件建立了涂油室的有限元电场模型,然后结合实验室最新的实验现象对涂油室上刀梁电极进行高压电场有限元分析和结构优化,分析刀梁尖端附近附加介质时电场的分布规律及场强最大值变化特点,得到刀梁电极的优化结构.优化后结构可以明显降低涂油机工作时电极所加电压,为静电涂油机今后的改进提供了一定的依据.     

Cost optimization of submersible motors using a genetic algorithm and a finite element method

This paper presents an optimal design method to optimize cost of three-phase submersible motors. The optimally designed motor is compared with an industrial motor having the same ratings. The motor design procedure consists of a system of non-linear equations, which imposes induction motor characteristics, motor performance, magnetic stresses, and thermal limits. The genetic algorithm (GA) is used for cost optimization, and a software algorithm has been developed. As a result of the realized optimization, besides the improvements on the motor cost, motor torque improvements have also been acquired. The 2-D finite element method (FEM) is then used to confirm the validity of the optimal design. Computer simulation results are given to show the effectiveness of the proposed design process that can achieve a good prediction of the motor performance. Through the studies accomplished, it has been observed that submersible induction motors’ torques and efficiencies improve, their length reduces, and hence some material savings are obtained.     

CNC micromilling properties and optimization using genetic algorithms

Micromachining operations are mainly restricted to precision machining of two-dimensional microparts, usually performed on microelectrical discharge machining or microlaser computer numerical control (CNC) machine tools. However, micromilling can fully exploit computer-aided design/computer-aided manufacturing (CAM) software abilities, in order to achieve more complex three-dimensional micropart geometries. After fully defining the micromilling process parameters and related constraints, optimization methodologies, such as genetic algorithms, can be coupled with CAM software, thus obtaining optimal process parameters with very small calculation cost. In this study, CNC micromilling process is systematically presented, along with respective micromilling tools and the necessary industrial equipment for the processes. Genetic algorithm code was developed in Visual Basic, which optimizes the process and ultimately yields optimal parameter values, including all process particulars. Two test cases were presented, and results were discussed in terms of micropart quality, production time, and calculation cost.     

基于ALGOR的麻花钻受力有限元分析

以UG为平台创建标准麻花钻钻头三维模型,经过模型的简化,把所建三维CAD模型转化为有限元模型。利用网格划分技术对钻头进行网格划分和单元属性定义,最后施加约束条件进行有限元分析求解。找出应力集中处,可为提高钻头的切削性能和耐用度的研究提供依据。对优化钻头结构参数、改进钻头结构具有重要意义。     

A finite element beam analysis by interface matching

An alternative way of finite element beam analysis is presented. The beam deflection in an element is represented by the sum of general solution and particular solution. The general solution is approximated by using Hermite polynomials and the particular solution is obtained by applying zero boundary conditions at element boundaries. The inter-element stiffness matrices are obtained by requiring the continuity of moment and shear force across element boundaries. The inter-element stiffness matrices do not overlap each other to form the global stiffness matrix. The boundary conditions are explicitly specified. Numerical examples are provided for various boundary conditions and load conditions.

     

Inclusion of elastic deformation in rigid-plastic finite element analysis

A rigid-plastic finite element method combined with the effect of elastic deformation is proposed. In the present method, elastically and elastic-plastically deforming elements are mixed with rigid-plastically deforming elements in the deforming material. In this formulation based on an implicit scheme, the nodal forces for the rigid-plastic elements are equilibrated with those for the elastic and elastic-plastic elements at the end of each deformation step. The nodal forces for the elastic and elastic-plastic elements are derived by considering the effect of rigid-body rotation during deformation increment. The elastic-plastic element is transformed into the rigid-plastic one during the loading when the elastic strain increment is small. The reverse transformation is carried out in the unloading. This leads to a comparatively small computing time and the improvement of the calculated results. Plane-strain bending of a plate with a round punch is simulated by the present method under a mixed condition of elastic, elastic-plastic and rigid-plastic elements in the plate. Deformation behaviour in early stages of bending is successfully calculated. The calculated amounts of springback are in reasonable agreement with the experimental ones for aluminium plates because the stress distribution in the elastic regions without achieving yielding around the edges of the plate is taken into consideration.     

汽车轮毂的有限元分析及优化

从汽车的轻量化思想出发,针对某型号钢制轮毂的性能和设计尺寸,运用ANSYS软件进行了参数化建模和有限元分析,并根据计算出的轮毂强度对轮毂进行了结构优化,得到了轮毂的最优尺寸。本次研究为汽车轮毂的结构设计和性能测试提供了最优化结果,具有实用意义和借鉴作用。     

基于有限元分析的结构优化设计方法

提出了利用ANSYS优化分析功能对结构进行优化分析的方法,通过十杆桁架的优化分析介绍了用有限单元法解决实际问题,实现优化设计的全过程,说明了用ANSYS优化分析功能实现结构优化分析的可行性,从而为其它复杂结构的优化分析提供了新的方法和科学依据。     

基于有限元法的矩形薄壁梁轴向耐撞性能优化

矩形薄壁空心直梁是汽车纵梁经常采用的结构形式,并且是承受正面碰撞的主要部件,其结构的耐撞性及碰撞吸能优化是现代汽车研究的重要内容.以矩形薄壁梁为研究对象,基于动态有限元分析模型,利用LS-DYNA软件中的OPT模块技术,研究矩形薄壁梁横截面的边长比变化对其耐撞性能的影响,对薄壁直梁在轴向冲击载荷下的耐撞性能进行了优化仿真.优化结果表明,当矩形两个边长的比值为0.6时,结构的碰撞力峰值最小,吸收的塑性变形能最大,具有最好的耐撞性能.     

Stress propagation through jointed beam systems using finite element theory

The propagation of disturbances through connected beams is considered using finite element theory: the Timoshenko beam model is considered since it exhibits the correct propagation behaviour in single beams. The joint is examined and three joint models are introduced into the model, namely the rigid block model, the filament model and finally a flexible joint model. The numerical results so obtained compare favourably with experimental results produced at UMIST.     

Dynamic analysis of an axially moving beam subject to inner pressure using finite element method

A dynamic model of an axially moving flexible beam subject to an inner pressure is present. The coupling principle between a flexible beam and inner pressure is analyzed first, and the potential energy of the inner pressure due to the beam bending is derived using the principle of virtual work. A 1D hollow beam element contain inner pressure is established. The finite element method and Lagrange’s equation are used to derive the motion equations of the axially moving system. The dynamic responses are analyzed by Newmark-β time integration method. Based on the computed dynamic responses, the effects of inner pressure on beam dynamics are discussed. Some interesting phenomenon is observed.     

Comparative study of thermal post-buckling analysis of uniform slender & shear flexible columns using rigorous finite element and intuitive formulations

Thermal post-buckling analysis of uniform, isotropic, slender and shear flexible columns is presented using a rigorous finite element formulation and a much simpler intuitive formulation. The ends of the columns are axially restrained to move and consequently any temperature rise above the stress free condition of the column produces an equivalent constant compressive mechanical load that causes the column to buckle at a critical temperature. Further increase in temperature beyond critical temperature results in the thermal post-buckling phenomenon. As a result of constraints imposed on the axial displacement at the ends of the column, the post-buckling phenomenon is governed by the von-Karman strain displacement relation applicable to one dimensional problems. Empirical formula for ratio of nonlinear axial load to critical load (equivalent constant mechanical load for a given temperature rise) as a function of the central deflection are obtained using both the rigorous finite element and intuitive formulations for various boundary conditions. The boundary conditions considered are the classical such as hinged-hinged, clamped-clamped and clamped-hinged conditions and nonclassical boundary conditions like the hinged-guided or the clamped-guided conditions. Post-buckling analysis results pertaining to nonclassical boundary conditions are meagre in the literature. It is observed that results obtained from both the formulations are in excellent agreement for all boundary conditions considered. Also the accuracy and simplicity of the intuitive formulation is aptly demonstrated to slender and shear flexible columns.     

双点腐蚀管道的弹塑性有限元分析

在役的油气田长输管道中,管道的点腐蚀是常见的一种腐蚀缺陷,有单点腐蚀、双（多）点腐蚀与长腐蚀等,对于腐蚀管道剩余强度的计算与剩余寿命的预测,目前我国还没有统一的国家标准,而美国的B31G又较为保守。本文以四川天然气环网中北干线为研究对象,利用ADINA System8．0,对双点腐蚀管道,分别对不同剩余壁厚、不同内压、不同腐蚀点间距下,进行大量弹塑性有限元分析,等到了一些有参考价值的结论。     

A mixed-hybrid finite element for three-dimensional isotropic helical beam analysis

This paper presents a two node finite element with six degrees of freedom per node, able to model the behaviour of a three-dimensional isotropic helical beam with two constant radii of curvature (curvature and torsion radii). The formulation, which includes the shear strain effects, is based on the assumed resultant forces hybrid approach. The resulting forces approximation verifies exactly the equilibrium equations. Numerical results of samples and distribution of generalized forces along the helical beam are presented. Comparison with other models indicates that the presented element gives exact solutions.     

Design of PID-type controllers using multiobjective genetic algorithms

The design of a PID controller is a multiobjective problem. A plant and a set of specifications to be satisfied are given. The designer has to adjust the parameters of the PID controller such that the feedback interconnection of the plant and the controller satisfies the specifications. These specifications are usually competitive and any acceptable solution requires a tradeoff among them. An approach for adjusting the parameters of a PID controller based on multiobjective optimization and genetic algorithms is presented in this paper. The MRCD (multiobjective robust control design) genetic algorithm has been employed. The approach can be easily generalized to design multivariable coupled and decentralized PID loops and has been successfully validated for a large number of experimental cases.     

Joint optimization of spare parts inventory and maintenance policies using genetic algorithms

In general, the maintenance and spare parts inventory policies are treated either separately or sequentially in industry. However, since the stock level of spare parts is often dependent on the maintenance policies, it is a better practice to deal with these problems simultaneously. In this study, a simulation optimization approach using genetic algorithms (GAs) has been proposed for the joint optimization of preventive maintenance (PM) and spare provisioning policies of a manufacturing system operating in the automotive sector. A factorial experiment was carried out to identify the best values for the GA parameters, including the probabilities of crossover and mutation, the population size, and the number of generations. The computational experiments showed that the parameter settings given by the proposed approach achieves a significant cost reduction while increasing the throughput of the manufacturing system.